[sdiy] Passive Ring Modulator

[Tim Ressel]

Yo,

Well, okay, not quite passive. If one makes an
amplifier with a +/-1 gain, and the +/- 1 part is
controlled by a square wave, then you wind up with a
mixer. There is an opamp circuit that does this. Take
a basic inverting circuit gain = -1, and run the input
to the + input thru the same value resistor as used on
the - input. This circuit will have a gain of +1. then
short the + input to ground (fet or switch) and the
gain goes to -1. The square wave runs the switch.

--TR


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